The present invention relates to a high frequency module substrate device used in a high frequency module apparatus, and more particularly to a high frequency module substrate device used in a high frequency module apparatus constituting a micro-communication functional module mounted at various electronic equipments such as personal computer, mobile telephone, video equipment or audio equipment, etc. and having information communication function and/or storage function, etc.
Various information such as music, voice (sound) or image, etc. have been handled with ease also by small sized information processing device such as personal computer or mobile computer, etc. with digitization of data. Band compression of such information is realized by voice Codec technology or image Codec technology, and environment in which such information are easily and efficiently delivered or distributed to various communication terminal equipments by digital communication or digital broadcast is being arranged. For example, audio data and video data (hereinafter referred to as AV data) can be also received at the outdoors by mobile telephone.
Meanwhile, transmission/reception system for data, etc. is diversely utilized by construction of suitable network system also within small scale area including home. As a network system, attention is drawn to various next generation wireless systems like, e.g., wireless LAN system of 2.45 GHz band proposed in the IEEE802.11b, short-range wireless communication system called Bletooth, etc., and/or narrow band wireless communication system of 5 GHz band proposed in the IEEE802.11a along with very weak radio wave system using 400 MHz band or PHS (Personal Handy-Phone System) using 1.90 GHz band. In the transmission/reception system, by effectively utilizing such wireless network system, transmission/reception of various data and/or access to various communication networks or transmission/reception of data with respect thereto can be carried out with ease and without intervention of relay device, etc. at various places such as inside of home or outdoor, etc.
On the other hand, in the transmission/reception system, realization of compact, light and portable communication terminal equipment having the above-described communication function becomes indispensable. In the communication terminal equipment, since it is necessary to carry out modulation/demodulation processing of analog high frequency signal at the transmitting/receiving unit, a high frequency transmitting/receiving circuit by the superheterodyne system adapted for once carrying out conversion into intermediate frequency from transmit/receive signal is generally provided.
In the high frequency transmitting/receiving circuit, an antenna unit including an antenna and a changeover switch and serving to receive or transmit information signal, and a transmission/reception switcher for carrying out switching between transmission and reception are provided. In the high frequency transmitting/receiving circuit, a receiving circuit unit composed of a frequency converting circuit unit and a demodulation circuit unit, etc. is provided. In the high frequency transmitting/receiving circuit, a transmitting circuit unit composed of a power amplifier or a drive amplifier and a modulation circuit unit, etc. is provided. In the high frequency transmitting/receiving circuit, a reference frequency generating circuit unit adapted for delivering reference frequency to the receiving circuit unit and the transmitting circuit unit is provided.
In such high frequency transmitting/receiving circuit, there is employed the configuration in which the number of large functional components such as various filters respectively inserted between respective stages, local oscillator (VCO) and SAW filter, etc., and the number of passive components such as inductor, resistor and capacitor, etc. peculiar to the high frequency analog circuit such as matching circuit or bias circuit, etc. are very large. In the high frequency transmitting/receiving circuit, IC configuration of respective circuit units can be realized. However, filters inserted between respective stages cannot be taken into IC. For this reason, matching circuit is also required as external attachment component. Accordingly, the high frequency transmitting/receiving circuit becomes large as a whole. Thus, this constitutes great obstacle in miniaturization and realization of light weight of communication terminal equipment.
On the other hand, at the communication terminal equipment, a high frequency transmitting/receiving circuit by the direct conversion system of carrying out transmission/reception of information signal without carrying out conversion into intermediate frequency is also used. In such a high frequency transmitting/receiving circuit, information signal received by the antenna unit is delivered to demodulation circuit unit through transmission/reception switcher so that base band processing is directly carried out. In the high frequency transmitting/receiving circuit, information signal generated at the source is directly modulated into a predetermined frequency band without being converted into intermediate frequency at modulation circuit unit, and is transmitted from the antenna unit through amplifier and transmission/reception switcher.
Since such a high frequency transmitting/receiving circuit has the configuration adapted for carrying out direct detection without carrying out conversion of intermediate frequency with respect to information signal to thereby carry out transmission/reception, the number of parts such as filter is reduced so that simplification of the entire configuration is realized. Thus, configuration closer to one chip is expected. However, also in the high frequency transmitting/receiving circuit by this direct conversion system, countermeasure of filter or matching circuit disposed at the succeeding stage is required. In addition, since the high frequency transmitting/receiving circuit carries out amplification of one time at the high frequency stage, it becomes difficult to obtain sufficient gain. As a result, it is necessary to carry out amplifying operation also at the base band unit. Accordingly, there is the problem that the high frequency transmitting/receiving circuit requires cancel circuit for DC offset and additional low-pass filter, and the entire power consumption becomes large.
In both the superheterodyne system and the direct conversion system, as described above, the conventional high frequency transmitting/receiving circuits could not obtain sufficient characteristic with respect to the requirement specification such as miniaturization and/or lightweight, etc. of communication terminal equipment. For this reason, with respect to the high frequency transmitting/receiving circuit, various attempts are made in connection with module in which miniaturization is realized by simple configuration where, e.g., Si-CMOS circuit, etc. is caused to be base. Namely, one of such attempts is, e.g., a method of forming passive elements of good characteristic on Si substrate, and of making filter circuit and/or resonator, etc. on LSI, and further also integrating logic LSI of the base band portion to thereby manufacture the so-called one chip high frequency transmitting/receiving module.
In such Si substrate high frequency transmitting/receiving module, how inductor of good performance is formed on LSI becomes extremely important. In the high frequency transmitting/receiving module, for the above reason, e.g., a large recessed portion is formed in correspondence with the portion where inductor is to be formed of Si substrate and SiO2 insulating layer to form a first wiring layer in a manner faced to this recessed portion, and to form a second wiring layer which closes the recessed portion thus to constitute inductor portion. Moreover, in the high frequency transmitting/receiving module, as another countermeasure, a configuration such that a portion of wiring pattern is raised from the substrate surface so that it is caused to float in air is provided so that inductor portion is formed. Such high frequency transmitting/receiving modules both have the problem that the step for forming the inductor portion is extremely complicated so that cost is increased by increase of the step.
On the other hand, in one chip high frequency transmitting/receiving module, electric interference of Si substrate intervening between high frequency circuit unit of analog circuit and base band circuit unit of digital circuit becomes great problem. With respect to the high frequency transmitting/receiving module, there are proposed, e.g., a module in which SiO2 layer is formed on Si substrate thereafter to form, by the lithographic technology, a layer where passive element is to be formed, and a module in which a layer where passive element is to be formed is formed on glass substrate by the lithographic technology.
In the Si substrate high frequency transmitting/receiving module, passive elements such as inductor portion, resistor body portion or capacitor portion, etc. are formed along with wiring pattern within the layer where passive element is to be formed by the thin film formation technology or the thick film formation technology so that they are caused to be of multi-layer structure. In the high frequency transmitting/receiving module, terminal portions connected to internal wiring pattern are formed through via (junction throughole) on the layer where passive element is to be formed, and circuit elements such as high frequency IC or LSI, etc. are directly mounted onto these terminal portions by the flip chip mounting method, etc. Such high frequency transmitting/receiving module is mounted at, e.g., mother board (substrate), etc. to thereby partition the high frequency circuit portion and the base band circuit portion so that electric interference between both portions can be suppressed. However, while the high frequency transmitting/receiving module functions when respective passive elements are formed within the layer where passive element is to be formed, there is the problem that Si substrate having conductivity constitutes obstacle to satisfactory high frequency characteristics of respective passive elements.
In the glass substrate high frequency transmitting/receiving module, glass substrate is used as base substrate to thereby solve the above-described problems resulting from the Si substrate of the Si substrate high frequency transmitting/receiving module. In the high frequency transmitting/receiving module, passive elements such as inductor portion, resistor body portion or capacitor portion, etc. are formed along with the wiring pattern within the layer where passive element is to be formed by the thin film formation technology or the thick film formation technology so that they are caused to be of multi-layer structure. The high frequency transmitting/receiving module is caused to be of the configuration in which terminal portions connected to internal wiring pattern are formed through via, etc. on the layer where passive element is to be formed, and circuit elements such as high frequency IC or LSI, etc. are directly mounted onto these terminal portions by the flip-chip mounting method, etc.
In the high frequency transmitting/receiving module, glass substrate which has no conductivity is used so that the degree of capacitive coupling between glass substrate and the layer where passive element is to be formed is suppressed to have ability to form passive element having satisfactory high frequency characteristic within the layer where passive element is to be formed. In the high frequency transmitting/receiving module, in order that it is mounted onto, e.g., mother board (substrate), etc., terminal pattern is formed on the surface of the layer where passive element is to be formed, and connection to the mother board (substrate) is carried out by the wire bonding method, etc. Accordingly, in the high frequency transmitting/receiving module, terminal pattern formation step and wire bonding step are required.
In the one chip high frequency transmitting/receiving module, as described above, a layer where a passive element is to be formed of high accuracy is formed on base substrate. For the base substrate, in carrying out thin film formation of the layer where passive element is to be formed, heat resistance characteristic with respect to rising of the surface temperature at the time of sputtering, holding of focal depth at the time of lithography and the contact alignment characteristic at the time of masking are required. For this reason, the base substrate is required to have flatness of high accuracy, and is required to have insulating property, beat resistance characteristic and chemical resistance, etc.
The Si substrate and the glass substrate have such characteristics to permit formation of passive elements of low cost and low loss by the process different from LSI. In the Si substrate or the glass substrate, as compared to the method of forming pattern, etc. by printing or the wet type etching method of forming wiring pattern on printed wiring board used in the conventional ceramic module technology, formation of passive element of high dimensional accuracy is permitted, and the area of the element size can be reduced to about {fraction (1/100)} thereof. The Si substrate and the glass substrate also make it possible to increase the use limit frequency band of the passive element up to 200 GHz.
Such high frequency transmitting/receiving module is required to form pattern of the high frequency signal system through the wiring layer formed on Si substrate or glass substrate as described above, and to carry out supply wiring for power supply and/or ground or control system signal wiring. As a result, electric interference takes place between these respective wirings, and the problem of increase in cost due to the fact that wiring layer is formed so that it is caused to be of the multi-layer structure takes place. Moreover, the high frequency transmitting/receiving module is mounted onto one surface of interposer substrate and the entirety thereof is sealed by insulating resin so that package structure is realized. The interposer substrate is adapted so that pattern wiring layers are formed on both surfaces of the face and the back, and a large number of lands are formed around the area where the high frequency transmitting/receiving module is mounted. The package electrically connects this high frequency transmitting/receiving module and the lands by the wire bonding in the state where the high frequency transmitting/receiving module is mounted on the interposer substrate to carry out supply of power and/or transmission/reception of signal. Accordingly, at the high frequency transmitting/receiving module, wiring pattern for connecting these mounting parts and/or connection terminals to wire bonding, etc. are formed on the surface layer where high frequency ICs and/or chip components, etc. are mounted.
Since the high frequency transmitting/receiving module is caused to be of package structure through the interposer substrate as described above, there is the problem that thickness or area of the package becomes large. The high frequency transmitting/receiving module also has the problem that cost of the package is increased. Further, in the Si substrate or the glass substrate high frequency transmitting/receiving module, shield cover is provided in a manner to cover circuit elements such as high frequency IC or LSI, etc. mounted thereon. In this case, there is also the problem that such module becomes large by the structure employed for radiating heat produced from these circuit elements. Further, in the high frequency transmitting/receiving module, there was the problem that relatively expensive Si substrate or glass substrate is used so that cost is increased.
Meanwhile, in the general high frequency transmitting/receiving module 100 of the above-described superheterodyne system, etc., a receive signal received by an antenna 101 like antenna I/O circuit unit shown in FIG. 1 is passed through a band-pass filter 102 which passes only a predetermined carrier frequency band, and is then inputted to a low-noise amplifier 104 of the receiving side through a switch circuit 103. In the high frequency transmitting/receiving module 100, an output signal superimposed on a predetermined carrier frequency is inputted to the band-pass filter 102 through the switch circuit 103 switched to the output side from a power amplifier 105, and is passed through this band-pass filter 102. The output signal thus obtained is outputted from the antenna 101.
On the other hand, in the high frequency transmitting/receiving module, it is preferable that such module is commonly applied also to various wireless network systems in which carrier waves of different frequencies where the carrier frequency is caused to be 5 GHz or 2.45 GHz, etc. are used as described above. In such a common use type high frequency transmitting/receiving module 110, as shown in FIG. 2, for example, there is provided an antenna I/O circuit unit having band switching function to pass a signal superimposed on a carrier wave of frequency adapted when the system is used.
Namely, the high frequency transmitting/receiving module 110 comprises, as shown in FIG. 2, an antenna 111, a first band changeover switch circuit 112, a first band-pass filter 113 which passes carrier wave signal of frequency of 2.45 GHz and a second band-pass filter 114 which passes a carrier wave signal of frequency of 5 GHz which are connected in parallel to this band changeover switch circuit 112 so that path switching is carried out, a second band changeover switch circuit 115, an input/output changeover switch 116, and a broad band low noise amplifier 117 of the receiving side and a broad band power amplifier 118 of the output side. The first band changeover switch circuit 112 and the second band changeover switch circuit 115 become operative in an interlocking manner to constitute path of carrier frequency selected between the antenna 111 and the input/output changeover switch circuit 116.
In the high frequency transmitting/receiving module 110, switching operation of the first band changeover switch circuit 112 and the second band changeover switch circuit 115 is carried out in accordance with the system adaptation carrier frequency so that receive signal from the antenna 111 is delivered to the first band-pass filter 113 or the second band-pass filter 114 which has been selected. In the high frequency transmitting/receiving module 110, receive signal passed through each band-pass filter is inputted to the broad band low noise amplifier 117 through the second band changeover switch circuit 115 and the input/output changeover circuit 116 switched to the input side.
In the high frequency transmitting/receiving module 110, switching operation of the first band changeover switch circuit 112 and the second band changeover switch circuit 115 is carried out in accordance with carrier frequency adapted to the system. In the high frequency transmitting/receiving module 110, an output signal superimposed on a predetermined carrier frequency is inputted to the selected band-pass filter 113 or 114 through the input/output changeover switch circuit 116 switched to the output side of the broad band power amplifier 118 and the second band changeover switch circuit 115. In the high frequency transmitting/receiving module 110, the output signal is passed through the band-pass filter 113 or 114, and is outputted from the antenna 111 through the first band changeover switch circuit 112.
In the high frequency transmitting/receiving module 110, since plural circuit units for carrying out band switching as described above are connected to the antenna 111, the circuit configuration becomes complicated. In the high frequency transmitting/receiving module 110, e.g., functional components which can process two kinds of carrier frequencies are used as the antenna 111 and/or amplifiers 117, 118 are used so that countermeasure is taken without increasing the number of parts (components), but it is necessary to increase the number of band changeover switches 112, 115 and/or band-pass filters 113, 114 in accordance with kind of carrier frequency.
In the high frequency transmitting/receiving module 110, for the above reason, there are the problems that cost is increased by increase in the number of parts and realization of adaptation to miniaturization required becomes difficult by enlargement of the mounting substrate. In the high frequency transmitting/receiving module 110, since a large number of circuit elements are mounted with high density on mounting substrate of a limited area, there was the problem that passing loss by respective circuit elements is increased so that the characteristic is deteriorated. In the high frequency transmitting/receiving module 110, since circuit patterns are formed every carrier frequencies on the mounting substrate, there is the problem that it is necessary to provide solid plane ground, etc. which ensures mutual isolation so that the circuit pattern design becomes troublesome. Thus, there is the problem that the mounting substrate also further becomes large.
Meanwhile, in the high frequency transmitting/receiving module, when such module is used in a band where the carrier frequency is above about 5 GHz, the circuit configuration using the so-called distributed parameter element such as Transmission Line, Coupling Line or Stub, etc. can still more improve the characteristic with respect to the circuit configuration using the so-called lumped parameter (concentrated constant) element such as inductor or capacitor, etc. Moreover, in the high frequency transmitting/receiving module, according as the frequency band of carrier wave used increases, band-pass filter (BPF), etc. is constituted by distributed parameter element as functional element, and elements such as inductor or capacitor, etc. are used as restricted functional component such as choke or decoupling, etc.
Namely, in the high frequency transmitting/receiving module, in the case where frequency of carrier wave is 2.45 GHz, wavelength dobles as compared to the case where frequency of carrier wave is 5 GHz As a result, when such module is constituted with lumped parameter element, element size becomes large. Accordingly, the high frequency transmitting/receiving module is caused to be of the configuration in which band-pass filter of lumped parameter design and band-pass filter of distributed parameter design are mounted on the mounting substrate in a mixed manner in the case where common specification of carrier wave having frequency of 2.45 GHz and carrier wave having frequency of 5 GHz is realized.
The applicant of the present application has proposed, in the specification and drawings of PCT/JP02/04178 and the specification and drawings of PCT/JP02/04409, substrate device for high frequency module including a high frequency circuit unit in which a thin film layer is formed on a relatively inexpensive organic base substrate, and the surface of this thin film layer is flattened to form, as film, band-pass filter of distributed parameter design and spiral inductor of lumped parameter design of high accuracy. This high frequency module substrate device is characterised in that passive elements of high accuracy and/or high density wiring layer are permitted to be formed on base substrate so that high function, thin thickness, miniaturization and low cost are realized.
In the high frequency module, in order to realize miniaturization, it is effective that band-pass filter is formed on base substrate formed by base material having high dielectric constant such as Si substrate or glass substrate, etc. Namely, in the high frequency module, base substrate of high dielectric constant is used so that different wavelength contractions take place at micro-strip line (surface layer) and strip line (inner layer), thus making it possible to shorten resonator length used for filter. The wavelength contraction takes place at λo/√{square root over (εw)} at the surface layer, and takes place at λo/√{square root over (εr)} at the inner layer (εr: specific dielectric constant of base substrate).
Here, λo is wavelength in vacuum, εw is effective specific dielectric constant and dielectric constant determined by the electromagnetic distribution of air and dielectric body, and εr is specific dielectric constant.
In the above-described high frequency module substrate device, since spiral inductor is constituted in the area of design sufficiently smaller than wavelength by the lumped parameter design, there is no possibility that influence of wavelength contraction may take place. In the high frequency module substrate device, since spiral inductor outputs high Q value as inductor, it becomes necessary to reduce parasitic capacity by coupling to the ground layer or the peripheral metallic pattern of the base substrate.
In the high frequency module substrate device, it is preferable to form base substrate by organic substrate material having a specific dielectric constant as small as possible in order to reduce the parasitic capacity of spiral inductor to realize improvement in the characteristic. Such substrate material is extremely effective because unnecessary parasitic capacity is similarly reduced also with respect to lumped parameter element such as MIM capacitor (Metal Isolator Metal Capacitor) or thin film resistor, etc.
The distributed parameter element and the lumped parameter element have characteristics contrary to each other with respect to the dielectric constant specification of the base substrate as described above. Accordingly, in the high frequency module substrate device, the base substrate is required to have such a selection to exhibit either one of the characteristics of the distributed parameter element and the lumped parameter element and to sacrifice the other characteristic, and has the problem that the characteristics of the both elements cannot be performed at the same time. In the high frequency module substrate device on which plural circuit units for carrying out band switching are mounted, since band-pass filters are constituted by the lumped parameter design and the distributed parameter design in accordance with carrier frequency band, such problem further becomes great.